Spray a large skillet with cooking spray and heat over medium to high heat, then add the spinach leaves. Cook until the spinach starts to wilt, about 5 minutes. Add the diced tomatoes and cream cheese and stir together, cooking for another couple of minutes and until cream cheese is fully melted down and combined. Transfer the spinach/tomato mixture to a large plate lined with a paper towels (to absorb excess moisture) and set aside.Place the skillet back on the burner and pour the egg whites in and add seasonings. Use a spatula to stir them around as they cook, for about 5-7 minutes, until they are scrambled. Remove from heat and set aside.Fill warmed tortillas with egg whites, spinach mixture and crumbled feta.Fold one end of the tortilla burrito-style and enjoy! Store any leftovers, wrapped and in a sealable baggie in the fridge. Freezing is also an option. Reheat burritos by placing in the microwave for approximately 2 mins.